Investigation of physical properties of Ni1-xBx/NiOy core/shell magnetic nano-particles (MNPs)

In this work, Ni/NiOy core/shell magnetic nanoparticles (MNP) synthesized by polyol method were optimized their structural and magnetic properties by using different reducing agents (EG, 1,2H) and surface active agents (NaOH, OA/OY). The most suitable reducing agent and surfactant for these properties were determined as 1,2-Hexadecanediol and Oleic Acid/Oleylamine (1,2H-OA/OY), respectively. After the optimization process, the Boron-doped Ni1-xBx/NiOy (x=0.0, 0.05, 0.10, 0.15) core/shell MNPs produced using the appropriate reduction agent and surface active agent were synthesized by the polyol method. Structural and magnetic properties of the samples were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Physical Property Measurement System (PPMS). The average particle sizes of Ni1-xBx/NiOy (x=0.0, 0.05, 0.10, 0.15) core/shell MNPs were found in the range of 3-5 nm from the SEM photographs and it is observed that the B3+ ions were distributed homogeneously in the structure. From the XRD spectra of the samples, it was determined that the addition of B did not cause any change in the cubic structure of Ni. It is observed from the temperature and magnetic field dependence magnetization measurements that magnetization of Ni/NiO core/shell MNPs increases with increasing Boron concentration from 5 to 15%. One can deduced that this increment in the magnetization comes from the resulting of strengthening the Ni-B ferromagnetic interaction. The highest saturation magnetizations under 1 T magnetic field were found as ~37 emu/g and ~30 emu/g at 10 and 300 K, respectively. It is expected that the results will contribute to the MNP family used in bio-nanotechnology and this new generation MNPs will be used as materials in biotechnology applications. In addition, these materials can also be used in magnetic memories when high magnetization data are taken into consideration. Because of all these results and potential applications, it is doubtless that the work done will contribute seriously to the both literature and applications in the industry.